Isabelle Cohen
Isabelle Cohen headshot
Year: 2023
Faculty Advisor: Andre Kessler
Mentor: Ethan Bass

Investigating the Effects of Dark Septate Endophytes on Arbuscular Mycorrhizal Fungi

Arbuscular mycorrhizal fungi (AMF) are soil microorganisms that form symbiotic relationships with plants through root colonization. AMF inhabit more than 80% of terrestrial plant species and transfer inorganic nutrients, such as phosphorus and nitrogen, through the cortical root cells of their host. In return, the AMF receives carbohydrates and lipids. Dark septate endophytes (DSE) are another group of root-colonizing fungi, named for their high melanin content and internal cell walls. Little is known about DSE and if they compete with other root colonizing fungi for space and nutrients in the rhizosphere. The purpose of this study was to determine if Leptodophora sp. (DSE) competes with Rhizophagus irregularis(AMF) through the secretion of anti-fungal metabolites. We performed an in vitro experiment by inoculating Rhizophagus irregularis spores with different concentrations of extracts from Leptodophora sp. cultures and observed the extracts’ effect on spore germination and hyphal elongation. We found a negative relationship between the concentration of Leptodophora sp. extract and both germination and elongation, suggesting that the inhibition is linked to DSE metabolites. A larger sample size over a longer observation period may provide more definitive results and insight into the nature of the interactions between these fungi.

>My work this summer taught me a wide range of techniques involved in chemical ecology research. This has included culturing different types of fungi and gaining experience with instruments such as the centrifuge and the high performance liquid chromatography machine. I also had the opportunity to practice my science communication skills through writing a research proposal, designing a poster, and recording daily procedures and results in my lab notebook. The guidance and enthusiasm of my mentor and the people around me made this program a lot of fun, and I enjoyed meeting other high school and undergraduate students with similar interests. Thanks to this positive experience, I am more confident in my decision to study science in college and pursue a career in research.